1. Technical Field
The present invention relates to a recording method using a glitter ink jet ink.
2. Related Art
In the field of printing called special color printing, there has recently been a marked increase in the amount of production of records in which a glitter image is formed on the recording surface. Methods such as pressing a metal-deposited foil against a recording medium to transfer an image (hot stamping) or applying a gold-silver ink which contains metals serving as coloring materials have been practically used in order to produce such glitter images.
Further, a method is known in which an ink containing a glitter pigment (hereinafter, referred to as “glitter ink”) is ejected by an ink jet method to produce a record. An example of such a method is disclosed in JP-A-2008-174712. Recording methods using a glitter ink are advantageous in that glitter images can be readily formed as well as in that various kinds of images can be produced easily.
From JP-A-2008-174712, a glitter ink is known which contains a metal such as silver-aluminum serving as a coloring material. Images that are recorded using such a glitter ink (metallic images) exhibit metallic gloss with high shininess immediately after being printed. However, the images are discolored and the glitter (gloss) is decreased more quickly than images produced using general color inks (color images). Further, the decrease in glitter is more noticeable to human eyes than fading (discoloration) of usual color images.
The major cause of degradations such as gloss reduction and discoloration is lights such as UV rays present in the sunlight. In particular, there is a tendency for glitter gloss to easily deteriorate in a color glitter image print section in which a color ink has been printed over a glitter ink print section. This deterioration is caused by poor lightfastness due to some effect caused by the color ink.
A possible approach to prevent a decrease in gloss is for a glitter ink to contain additives that are effective in preventing the discoloration of glitter pigments, such as discoloration inhibitors (antirust agents) and UV absorbers. However, some of these additives are not desirable for use from the viewpoints of safety and environmental friendliness. Further, some additives can adversely affect properties of inks. Furthermore, the discoloration of metallic images cannot be prevented at times even by the addition of UV absorbers.
Although print sections that are recorded using a glitter ink exhibit glitter with very high shininess immediately after being printed, they are degraded, for example decreased in gloss and discolored, by lights such as UV rays present in the sunlight much more quickly than print sections produced with general color inks. Such degradations are correlated with the amount of glitter coloring material per unit area of the print section. The higher the content of a glitter coloring material, the smaller the degradations. Provided that images are produced using the same ink, the degradations tend to be suppressed with increasing amount of ink dots per unit area. Thus, in order to prevent the degradation in gloss and produce metallic images with excellent lightfastness, a glitter ink is often designed so as to contain additives that are effective in preventing the discoloration of glitter pigments, such as discoloration inhibitors and UV absorbers. However, it has been pointed out that some of these additives are hazardous in terms of safety and environmental friendliness. Further, some of the additives cause marked changes in properties of an ink in a short time, often resulting in an unsatisfactory ink composition.